Regulation of Apoptosis by SYB in HepG2 Liver Cancer Cells is Mediated by the P53/Caspase 9 Axis

Objective: To explore the function of miR-34a in promotion of apoptosis by SYB. Methods: In this study, the most effective concentration of SYB was determined by measuring cell proliferation. Relative miR-34a mRNA levels were detected by quantitative RT-PCR. Apoptosis was assessed using Annexin- V/PI assays, whereas protein levels of p53, caspase 3, caspase 9, caspase 8 and Bcl2 were evaluated by western blotting. Results: Minimum HepG2 cell growth was observed after 36h of exposure to 150 nmol/L SYB. miR-34a expression was highest 40min after the addition of SYB. SYB slightly decreased the abundance of Bcl-2, but increased the abundance of p53, caspase 3, caspase 9 and caspase 8. SYB failed to alter miR-34a expression when p53 was inhibited. Bcl-2 abundance remained low over time, whereas the abundance of caspase 3, caspase 9 and caspase 8 gradually increased. Inhibition of p53 promoted HepG2 cell growth in comparison with that of the control group. miR-34a was silenced to assess the role of miR-34a in the inhibitory effect of SYB on HepG2 cell growth. When p53 was silenced, protein abundance of Bcl2, caspase 3, caspase 8 and caspase 9 remained unchanged following the addition of SYB; moreover, HepG2 cell growth was increased. Conlusion: SYB represents a promising therapeutic approach for liver cancer patients.

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